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Discussions about life in the universe should be posted in this thread (I know its name doesn't make it very obvious).

As to what place would be the best for a developing civilization, there really is no answer to that. There are pros and cons to every different place, and what impact those places have depend greatly on the culture of the people there. And the nature of their world and star system would have a tremendous impact as well. Their galactic location would ultimately be of secondary importance (at least until later in their development). Due to the sheer number of unrelated variables and social factors in this scenario, there really is no right answer.

Good thread and good answers all around! I also share HarbingerDawn's disagreements/doubts on the Rare Earth Hypothesis, and he discussed the main reasons fairly well. I'll detail my own beliefs on the prospect of life elsewhere in the universe below:

Simple Life: I believe that 'simple', single-celled life not only exists elsewhere in the universe, but is actually extremely common!

Reasons: -We understand reasonably well the conditions that lead to the development of life on Earth, and we know that such conditions are also extremely common elsewhere. -We know that life on Earth developed remarkably quickly -- within a billion (maybe even half billion!) years after its formation. -We know from observations and theory that terrestrial planets are very common. (Natural result of star formation process.) -We know that water and the essential building blocks of life are extremely common as well. (Natural result of stellar evolution and chemical processes in giant molecular clouds / protoplanetary disks) -There are other worlds in the solar system that appear promising as bearers of life. Mars has abundant evidence for once having a hydrological cycle, and currently has methane releases which may be biological in origin. Europa has a large subsurface ocean of liquid water, and may have similar environments to Earth's deep-sea vents which sustain complex ecosystems. -We have found numerous examples of organisms that can thrive in environments far more extreme than we originally thought possible, which greatly expands the possibilities for the habitability of worlds elsewhere. Extremophiles for the win! -I believe the 'Copernican Principle', which basically says we don't occupy a special/privileged place in the universe, also applies more generally to life and its distribution/commonality in the universe. (Philosophical argument) -Quote from Contact: "if it is just us... seems like an awful waste of space." (Ok, that's another Philosophical argument -- bad bad! Stick to science!)

Intelligent Life: I am much less confident on the occurrence of intelligent life (I mean intelligent on the level that humans are -- there're plenty of intelligent species on Earth, and intelligence in general is very difficult to define). My low confidence is especially due to a greater lack of evidence to weigh in on the matter. That said, I learn towards thinking it is rare, maybe very much so, but I also do not believe we're the only ones.

Reasons: -So far, we are the only sentient life on Earth, so sentience in general may be an uncommon evolutionary development. (Alternatively, as discussed below, it might just take a while to develop, and we're the first ones on this planet). -We know it took a very long time for complex life to develop on Earth. The Cambrian Explosion was only half a billion years ago. It could be, though is by no means certain, that it either just takes a while for conditions on a planet to become suitable for complex life (Earth has a really complex and chaotic climate history), or maybe it statistically takes a while on average for complex life to evolve in the first place. -Intelligent life might not last very long. (Carl Sagan often suggested this). Civilizations might tend to eradicate themselves after a fairly short period. I don't mean to say that we ourselves are at risk of imminent extinction, but I would still point out that we have already come very close to total nuclear catastrophe and are currently still doing a rather lousy job of maintaining our own planet's climate and ecosystems (life in general should be just fine, but for our own needs this is really distressing.) -Additionally, external factors could also result in the loss of an intelligent species -- meteorite impacts, supernovae, etc.

I'm actually currently taking a course on astrobiology, and we tend to discuss these sorts of topics during class. Fascinating field, even more so now that it can be approached in a more rigorous scientific fashion.

So if there is a more advanced civil. out there it will be literally hunting for planets like ours. Especially if they have consumed their resources. So all these ideas about an advance civil. being mature enough and ethical enough is very naive thinking: The more advanced they are, the more energy and resources they will need. I bet they are like locusts aka independence day and they go from earth to earth and suck every single drop of resource they can possibly get.

I think that if they are REALY intelligent they would go on a un-habited planet, because: 1. They could find a civility with hyper-powerful weapons 2. The could have consumed most of resources that they have on their planets (like us)

So maybe they are hunting for habitable planets and not habited planets, I hope they are not studyng us to understand if we are able to destroy them or not D:

The universe is not required to be in perfect harmony with human ambition.

Personally, I think the REH is more likely, directed mostly toward intelligent life. I think that life is probably more common than we think. Whether it is in our solar system I am highly doubtful, but whatever. INTELLIGENT life however I find highly unlikely, complex life fits into roughly the same spot as intelligent. Maybe we are the only sentient life form in the universe. Maybe the chances of sentient life being able to form and survive are so slim that it only came to be once and took a infinite universe of possibilities to come into being. If there is intelligent life out there or not I have no idea.

Anyway, if other sentient life exists out there and they have visited us they are probably not contacting us because they want to study us, finding sentient life of a primitive enough level to study would be interesting in learning how sentient life advances. Or maybe they are waiting to see if we are worthwhile introducing to the galactic community. Or, my personal favourite if they have found us, they don't care because we are in the uncharted backwaters of the unfashionable end of the western spiral arm and any aliens that come to earth are their equivalent of punk teens making fun of primitive lifeforms. What's more fun than kidnapping a primitive, sticking in instruments where they don't belong, then putting him back, to make fun of him, because few will believe him and most will laugh at him.

I recently watched through the wormhole with morgan freeman and the episode was named is the universe alive. At first i though what kinda question is that but then when morgan freeman said "but before you dismiss the claim you have to ask yourself what is life what makes you and everything else alive". So i though it was something i could watch and it was really cool and they took up alot of things like how often somethings hearth beets (il link the video so you can understand what i mean) And they think that the big bang might simply be the universe hearthbet. So il link the video it might sound crazy that something that 2 kelvin in space and maybe is 40 bilion light years in radius is alive but watch and listen and we might get the idea.As scientists peer across the galaxy, a new revelation emerges: The universe is shockingly organic. Are the secrets to the life and death of the universe hidden in physics, but biology? Could it be that the universe is alive? I couldent link it in the thread but if you want to watch and understand what i mean go on youtube and search is the universe alive and you will find it.

All of that in mind plus potential other unknown catastrophes a civilization faces, we may very well be the only ones in the entire Milky Way and if I may go so far to say, the only ones in our galactic local cluster.

I still think there is intelligent life out there but most likely nowhere near us.

I don't think the situation is that bleak but I agree to a point. The number of events that could have wiped us out coupled with the fact that we are constantly at war and have the nuclear arsenal to sterilize the planet after less than 500 years of complex technology doesn't give me much hope for finding advanced life nearby. Honestly, I think I may live to see the day humanity has to make a choice of survival/extinction.

That is a good analogy, assuming that we don't know anything about fish or biology at all, or very very little. Then it is hard to determine whether there might be other fish or not, since there is not enough data on which to base an estimate. That is like our current situation regarding exobiology.

I actually know the perfect analogy. If you take a glass and dip it in the ocean and there are no fish, does that mean there are no fish in the ocean?

I actually know the perfect analogy. If you take a glass and dip it in the ocean and there are no fish, does that mean there are no fish in the ocean?

I like this metaphor, but consider this: We humans have traveled our actual oceans many, many times, and from our experience we can say the above(literally). However, we have not traveled throughout the universe- in that regard all we've ever been able to take a close look at is the area where we submerged the glass (a.k.a., our solar system).

I do understand the logic here, and I'm not trying to disprove such logic. I just think the metaphor doesn't exactly fit.

1. They simply don't want to communicate, because our desire to find aliens was born by books and shi-fi films, but we are not sure that they have our same way of thinking...

2. They can have realized that no life exist in the galaxy so they are not interested on start a communicate until they don't find a civilizzated planet...

3. They never use radio waves for communications, in facts it's very primitive and with lot of limitations, maybe they founded a better way of communications that we don't know, so if they sent something we can't receive it....

4. What about WOW! signal?

The universe is not required to be in perfect harmony with human ambition.

I think the most likely explanation for the Fermi Paradox is that intelligence is very unlikely to evolve. I think life might be quite common, but intelligence a relatively rare evolutionary path. There probably are very few intelligent species in our galaxy; and even if there are as many as a thousand of them the average distance between them will still be about 3000 lightyears. The second part of it is that I think faster than light travel really is impossible, and travel at speeds close to light speed as good as impossible. I think most civilisations would mainly settle their own solar system, and only very rarely go to the stars.